1. Field of the Invention
This invention relates to closures for sealing nozzles, and more particularly to a plug for removably resealing the distally tapering nozzle of a container having extrudable air-curable material such as caulking and adhesive, to prevent leakage and hardening
2. Description of the Related Art
Sealant and gluing materials such as caulking and construction adhesives and other air-curable materials are commonly sold in rigid paper or plastic cylindrical tube, cartridge-type containers from which the material is extrudable. Such tubes typically include a conically tapering dispensing nozzle with a distally tapering bore therethrough, made of a soft plastic and attached proximally to a tube end and terminating distally in a sealed tip so that the material is isolated from air until ready for use. The relatively wide proximal end of the nozzle is often superposed over a foil or film seal covering a circular aperture in the tube end, so that after the nozzle tip is severed a thin rigid tool must be inserted through the nozzle to pierce the seal. Depending on the particular application, the user is advised by the manufacturer to precisely cut the tip so that the opening formed will extrude a bead of appropriate size. Typically, the diameter of this dispensing aperture is between xe2x85x9-inch and {fraction (5/16)}-inch, but may be larger. The tube is then inserted into a gun or similar device which applies pressure to a piston-like plunger in the rear of the tube so as to force material through the nozzle and out the tip opening. If sufficient material has been extruded to complete the job at hand but the tube contents are not exhausted, the user is faced with the problem of closing the opening so that air cannot leak in. Otherwise residual material in the nozzle as well as unextruded material in the tube will harden due to exposure to air, precluding future reuse. A common practice is to insert a nail or screw into the opening but because the opening size is non-standard and the choice of nails and screws at hand is likely to be limited, an ad hoc fit sufficiently tight to create an airtight seal is unlikely. If the material inside the nozzle does become hardened and is mainly near the tip, another practice is to cut away enough of the nozzle so that the hardened material is substantially removed, and then use a piercing tool to open a conduit to unhardened material within the tube. However, shortening the nozzle changes the size of the opening so that the size of the extruded bead is undesirably increased.
Plugs for resealing a nozzle attached to a container of air-curable extrudable material are known in the art. U.S. Pat. No. 6,223,957 to R. G. Hoppe discloses a conically tapering plug which is inserted into the nozzle through the tip opening until a tight fit is obtained. In a preferred embodiment the plug outer wall is generally smooth. In three alternate embodiments the outer wall includes discontinuities, specifically threads, steps, or ridges. Use of discontinuities allows a user to apply frictional force by twisting the plug as it is inserted, providing an xe2x80x9cinsertion interference fitxe2x80x9d and thus a greater sealing effect. The plug may be attached to a housing to which is also attached a spike for puncturing the tube end seal.
U.S. Pat. No. 5,248,071 to C. D. Ray discloses a nozzle and cap assembly for resealing a tube of caulking material, sealant, adhesive or the like. The assembly, intended to replace a standard dispensing nozzle, includes a nozzle having exterior threaded sections of varying diameter located along its length, and a cylindrical cap sealed at one end and having interior threaded sections of varying diameter along its length for engaging the exterior threads on the nozzle, thus forming an air-tight seal when the cap is screwed onto the nozzle.
U.S. Pat. No. 5,295,601 to R. F. Bostelman discloses a cap for resealing a caulking tube cartridge to prevent premature drying out of the material stored within the cartridge and also to prevent blockage within the nozzle. The cap includes a plug member having a tubular threaded metal insert and two integral wings, and a tapered orifice retainment rod. In an alternate embodiment the plug member also has integral interior threads. The rod is inserted into the nozzle until the nozzle tip is engaged within the tubular insert. Using the wings the plug member is then rotated until the metal insert threads or the integral threads engage the outside surface of the nozzle.
U.S. Pat. No. 5,154,327 to K. D. Long discloses a sealable nozzle adaptor for use with a caulking tube cartridge which slides over the tube end. The adaptor includes a nozzle portion closely fitted over the dispensing nozzle, a base including a flexible skirt portion for engaging the tube end, a cap for closing and sealing the tip opening of the dispensing nozzle, and an elongated pin secured in the cap and extending into the nozzle portion.
U.S. Pat. No. 4,669,635 to D. E. Brookhart discloses a tool for clearing and sealing a dispensing nozzle. The tool includes a shaft with a plurality of barbs projecting from its surface, spaced around the circumference and along the length of the shaft. The tool is used to seal the nozzle tip by inserting the shaft so that at least some of the barbs are surrounded by flowable caulking in the tip. This caulking eventually hardens, surrounding and tightly engaging the shaft and barbs. The hardened material is removed from the tip by grasping the tool handle and pulling outwardly.
None of these references discloses a closure which provides air-tight repetitive resealing of a standard dispensing nozzle yet is inexpensive and therefore disposable, so that the permanently soiled closure may be discarded along with the depleted tube.
In view of the limitations of the related art, it is an object of the present invention to provide a plug capable of removably resealing the opening of a standard dispensing nozzle regardless of the opening""s size and contour.
Another object of the invention is to provide a plug assembly including a piercing shaft that can be fabricated as a unitary molding.
A further object of the invention is to provide an assembly wherein the piercing shaft is easily separated from the plug.
Yet another object of the invention is to provide a plug that is simple to use and inexpensive to buy, even in quantity.
Other objects of the invention will become evident when the following description is considered with the accompanying drawing figures. In the figures and description, numerals indicate the various features of the invention, like numerals referring to like features throughout both the drawings and description.
These and other objects are achieved by the present invention which in one aspect provides a plug assembly for removably resealing an aperture in a dispensing nozzle attached to a container of extrudable material. The nozzle is made of a deformable soft plastic and has an axially symmetric bore determined by a distally tapering interior surface. The plug assembly includes a plug including an upper portion attached to a conically tapering lower portion which has a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge determining a distal end having a preselected circumference. Each distally successive scoring edge is slightly smaller in circumference, and each scoring edge is canted rearwardly at a first angle to a common longitudinal axis. Each scoring edge has a leading edge surface making a second angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third angle with respect to the orthogonal axis. The leading and trailing edge surfaces form a sharp point. The circumference of the distal end of the plug lower portion is sized to enable penetration of the aperture by at least the leading scoring edge, thereby contacting and scoring at least one groove in an annular segment of the nozzle interior surface.
The plug assembly further includes a cylindrical piercing shaft having a first end attached to the plug distal end, and an opposed end terminating in a blunt tip. The first end is proximate to a groove circumscribing the shaft. The plug and shaft are breakably separable at the groove.
In another aspect the invention provides a plug assembly for removably resealing an aperture of a preselected circumference in a dispensing nozzle attached to a container of extrudable material. The nozzle is made of a deformable soft plastic and has an axially symmetric bore determined by a distally tapering interior surface. The plug assembly includes a plug including an upper portion having a planar top surface orthogonal to a plurality of convexly arcuate knurls, with each pair of neighboring knurls separated by a concavely arcuate depression. The plug further includes a circumferential skirt, having a polygonal plurality of planar edge segments, attached to the plug upper portion. The plug further includes a conically tapering lower portion, attached to the skirt, having a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge determining a distal end. Each distally successive scoring edge is slightly smaller in circumference. Each scoring edge is canted rearwardly at a first angle to a common longitudinal axis. Each scoring edge has a leading edge surface making a second angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third angle with respect to the orthogonal axis. The leading and trailing edge surfaces form a sharp point. The circumference of the distal end of the plug lower portion is sized to enable penetration of the aperture by at least the leading scoring edge, thereby contacting and scoring at least one groove in an annular segment of the nozzle interior surface.
In yet another aspect the invention provides a method for removably resealing an aperture in a dispensing nozzle attached to a container of an extrudable material. The distally tapering nozzle is made of a deformable soft plastic and has an axially symmetric bore determined by a distally tapering interior surface. The method includes the step of fabricating a plug including an upper portion attached to a conically tapering lower portion which has a multiplicity of successively contiguous circumferential scoring edges terminating in a leading scoring edge determining a distal end. Each distally successive scoring edge is slightly smaller in circumference. Each scoring edge is canted rearwardly at a first angle to a common longitudinal axis. Each scoring edge has a leading edge surface making a second angle with respect to an axis orthogonal to the longitudinal axis and a trailing edge surface making a third angle with respect to the orthogonal axis. The leading and trailing edge surfaces form a sharp point. The circumference of the distal end of the plug lower portion is sized to enable penetration of the aperture by at least the leading scoring edge. The method further includes the step of penetrating the aperture with at least the leading scoring edge, thereby contacting and scoring at least one groove in an annular segment of the nozzle interior surface. The method further includes the step of screwing in the plug so as to penetrate further into the nozzle bore and create additional grooves in the surface segment as the points of additional scoring edges contact the surface segment.
A more complete understanding of the present invention and other objects, aspects and advantages thereof will be gained from a consideration of the following description of the preferred embodiment read in conjunction with the accompanying drawings provided herein.